get_setupcfg_version might ignore setup.cfg values in some circumstances

[ceball]

In converting from py3 to py2, I think I misread/didn't read the py2 docs:

 ConfigParser.get(section, option[, raw[, vars]])

    Get an option value for the named section. If vars is provided, it must be a dictionary. The option is looked up in vars (if provided), section, and in defaults in that order.

I think I used vars to supply a default if not present in section. Seems like I need to use a try/except NoOptionError instead.